Port 4393American Printware RXSpooler Protocol

TCP port 4393 is assigned to American Printware RXSpooler, a protocol with no widely documented public deployments.

transport: tcp
in transit: cleartext
assignment: official
risk: 1/10
lookups: 0

also known as apwi-rxspooler

Technical Details

what runs on :4393

American Printware RXSpooler Protocol is registered on port :4393 over tcp to Lech Lakomy, assigned February 2009. We don't have a technical write-up for it beyond the IANA registry entry.

In nmap's internet-wide scan data this port is never observed open, so if it's open on your network it's more likely a custom or misconfigured service than the registered one.

find what's listening on :4393

this machine

# linux
sudo ss -tlpn 'sport = :4393'

# macos / bsd
sudo lsof -nP -i :4393

# windows (then: tasklist /FI "PID eq <pid>")
netstat -ano | findstr :4393

another host

nmap -sV -p T:4393 <host>

run it? the handshake, the implementations you meet in the wild and the flags that matter come from the engineers who do.

add technical details

Security Information

exposure of :4393

risk score

1/ 10safe

routine exposure. this port is rarely the way in on its own — keep it patched and logged and move on.

in transit

cleartext

credentials and payloads are readable by anyone on path

assignment

official

registered with iana for this service — scanners fingerprint it by number

reachable over

tcp

every listening transport is another surface to filter at the edge

security overview

no security notes recorded for :4393 yet

known exploits, hardening advice, what a compromise looks like — suggest an edit if you know its exposure.

Record

iana registry entry

port: :4393
service: American Printware RXSpooler Protocol
transport: TCP
encryption: cleartext
assignment: iana registered
risk: 1/10safe
category: uncategorised
usage: IANA assigns TCP/4393 to the American Printware RXSpooler Protocol, registered by Lech Lakomy in 2009. Its implementation and typical deployment are not widely documented.
lookups: 0rank 993
added: 2026-10-04
updated: 2026-10-04
references: IANA service name registry — port 4393

Something wrong?

This record is maintained by the engineers who use port 4393. Every field on it is editable — change what's wrong, say how you know, and a reviewer publishes it, usually within a minute. Last touched 2026-10-04.

01edit any field on a page of its own
02a model checks it for accuracy and spam
03clean and confident goes live immediately

edit this record →back to the registry

Related Ports

browse categories →

ports registered around :4393, by lookups.

port	service	proto	category	risk	views
:4433	Axence nVision	TCP	Security	caution	8.9k
:4343	Wrapper: Offline	TCPUDP	Gaming	caution	1.7k
:4378	Cambridge Pixel SPx Display	TCPUDP	—	safe	0
:4361	NavCom Discovery and Control	UDP	Network Services	safe	0
:4447	N1-RMGMT	TCPUDP	—	safe	0
:4404	Asigra DS-System Monitoring/Management	TCPUDP	System	safe	0
:4449	PrivateWire	TCPUDP	—	safe	0
:4443	Pharos	TCPUDP	—	safe	0

risk mix of the 8 listed

safe75%
caution25%

0 of 8 encrypted

Port :4393American Printware RXSpooler Protocol

Technical Details

Security Information

Related Ports

Port 4393American Printware RXSpooler Protocol